5 Answers
5

You may get some oxidation of the "specialty" wort letting it sit like that.
You aren't really saving any time though. Start your steep in cold water while you heat it up. By the time its at 160F you are generally good to pull the grains out and keep on heating to boiling. I know most instructions when I started extract and grain brewing says to steep in 150 water or something like that, but there is no flavor difference to just start them in the cold water and start heating.

Wort juice will sour if left exposed to air below 150F. You can put it in a sanitized, sealed container, but I wouldn't leave it for more than 18 hours. Longer if you refrigerate it. But all of this sounds like more work and more risk than just steeping it when you need it.

I've done it maybe 5-6 times and there's no problem. I keep the liquid from the steeping refrigerated overnight and boil it the next day. But as has been said, there may not be much time saving from it. If you think it would help you, there's no problem with it, though.

With the 'tea' being added to your 60 minute boil, and as long as you follow good sanitation procedures, I don't see any major problems that you would run into.

But, you can much more easily just steep your grains in your brew pot while bringing your water up to a boil. This won't add time to your brew day, and will save you time having to deal with creating and properly storing your 'tea' days before.